PURPOSE: To easily knockout when a tapered square tube is drawn.
CONSTITUTION: The tapered square tube 4 is obtained by drawing a base stock square tube by a male die 16 and a female die 19 with the initial pressing of a ram 20. At that time, the tapered square tube 4 is brought into press- contact with the inside surface 19a of female die 19, an upper bolster 25 is inserted between the lower surface of ram 20 and the upper surface of a knockout block 22 and a lower bolster 23 is inserted in the lower part of female die 19 before the second pressing of ram 20. When the ram 20 is lowered, lowering of female die 19 is stopped by the lower bolster 23, the knockout block 22 is directly applied with the main pressurizing force of ram 20 with the upper bolster 25 and the tapered square tube 4 which is in press-contact with the inside surface 19a of female die 19 is knocked out by push-lowered. Since strong main pressurizing force of a press machine is utilised, knockout work is smoothly carried out.
KONO TAKEO
MIYATA TSUTOMU
TOMITA MASANORI
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